We have seen issues where redeeming a content code on Xbox.com can cause some issues with receiving the content on the Xbox One. If you have redeemed the Season Pass on Xbox.com, you will need to follow these steps in order to download the Season Pass and get access to that content:
1. Go to Home.
2. Go to My Games and Apps.
3. Select Trials Fusion.
4. Push the Select button. (The right black button with three lines on it)
5. Select Manage Game
6. Select Install Trials Fusion Season Pass (May be displayed as ULC 10.)
After downloading the Season Pass, you should be able to see the content within the game.